Treatment of lubricating oils



-Patented Feb. 25, 1936 TREATMENT or LUBRICATING OILS Alan Arnold Griflith and William Helmore, South Farnborough, England, assignors to C. C. Wakefield & Company Limited, London, England, a British company No Drawing. Application November 9, 1934, Serial No. 752,311. In Great Britain August 1,

3' Claims.

This invention is for improvements relating to lubricating oils and. has for an object toprevent their deterioration in use without detriment to their lubrication properties.

5 It is well-known that one of the chief defects experienced with lubricants, for example in internal-combustion engines, is the formation in-- the oil, often after a very short period of running, of sludge and gums and other deposits. It is thought that these deposits are caused by oxidation of the oil at the high temperatures obtaining on the cylinder and piston walls and in the bearings. Oxidation may also occur when the oil mixed with air is in the form of a mist in the crankcase.

It has already been proposed in prior British specifications Nos. 295,230 and 398,222 to minimize theformation of these deposits by adding to the oil small quantities of organic compounds .of

lead and of tin.

According to this invention, a lubricant comprises a lubricating oil having dispersed therein a small quantity of an organic compound of chromium. Preferably an oil-soluble compound 25 of chromium is selected in order that the compound may more easily be mixed with and uni formly distributed throughout the oil.

A feature of the invention ccnsists in that chromium oleate is added to the'lubrieating cii. A further feature or? intention cnnsasts in that the chromium compound is added to the oil in quantities of about 1% by weight of the oil.

It has been found that the organic compounds of chromium have a markedly beneficial effect as 35 set out below when used, for example, in the lubricating oils of internal-ccmhusticsa shoes or the like.

In one test, chromium oleate was added to a mineral oil to the extent of about by weight of the oil and it was found that, not only was the formation of the deposits minimized over a range of temperature corresponding with the temperatures obtaining in an internal-combustion engine, but also such deposits as were formed had a soft 5 and non-adherent character as distinct from the hard, varnish-like deposits obtained when an un-- treated mineral oil was subjected to a similar test.

It has also been observed that when using an oil,,treated with an organic chromium compound, the corrosion of the steel and iron surfaces was less than when an untreated oil was used. The use of these compounds should greatly reduce the wear of the steel cylinder walls and cast-iron pistons of internal-combustion engines.

It will be appreciated that the present invention is not restricted to any particular type of lubricating oil but that all lubricating oils, whether vegetable, mineral or blended oils, may be treated.

We claim:--

1. A fluid lubricant comprising a lubricating oil having dispersed therein chromium oleate up to 1% by weight of the oil, the said chromium oleate being effective as an anti-sludging agent in 25 an internal combustion engine.

2. A lubricating oil having dispersed therein up to 1% of a sludge-preventing substance characterized by an addition of chromium oleate. the said chromium oleate being efiective as an antisludging agent in an internal combustion engine.

3. A fluid lubricant comprising a lubricating oil having dispersed therein about 1% by weight of chromium oleate, the said chromium oleate being effective as an anti-sludging agent in an internal combustion engine.

ALAN ARNOLD GRIFFITH. WILLIAM HELMORE. 

